Start-up aims to revolutionize print with electronic ink
11/01/2001
by Mark A. DeSorbo
Prototypes of paper-like, flexible displays could emerge from modified photolithography cleanrooms as soon as next year.
Hybrid chipmaker E Ink Corp. (Cambridge, MA) believes ordinary paper may become a thing of the past now that the start-up has begun developing flexible transistors for its electronic ink displays in a recently completed facility in nearby Woburn, MA.
"Despite the current economic climate, E Ink is investing heavily in R&D," says Jim Iuliano, president and chief executive. "Our new semiconductor facility moves us closer to RadioPaper, E Ink's ultimate vision for a wireless display that looks and feels like paper."
The 9,500-square-foot facility has two cleanrooms, an ISO Class 4 (Class 10) and an ISO Class 6 (Class 1000) that are packaged in a box-within-a-box concept that occupies 2,000 square feet and has a traditional bulkhead mount and a service chase, says Michael McCreary vice president of research and development for E. Ink.
"The whole purpose of the facility is to develop thin-film transistors, half plastic with the other half being a traditional glass-back pane," says McCreary. "We believe this is the first cleanroom dedicated to flexible thin-film transistors."
 Michael McCreary, vice president of research and development for E Ink. |
According to E Ink, electronic ink is made up of millions of tiny microcapsules about the diameter of a human hair. Each microcapsule contains positively charged white particles and negatively charged black particles, which are suspended in a clear fluid. When a negative electric field is applied, white particles move to the top of the microcapsule where they become visible. This makes the surface appear white at that spot. An opposite electric field pulls the black particles to the bottom of the microcapsules where they are hidden. By reversing this process, the black particles appear at the top of the capsule, making the surface appear dark at that spot.
To form an E Ink electronic display, the ink is printed onto a sheet of plastic film that is laminated to a layer of circuitry. The circuitry forms a pattern of pixels that can then be controlled by a display driver. These microcapsules are suspended in a liquid "carrier medium," allowing them to be printed using existing screen printing processes onto virtually any surface, including glass, plastic, fabric and even paper.
"The electronic ink display is a laminate of two materials: The electronic ink of black and white pigments and the other half is the transistor array that allow pixels to form the image and the electronic ink to change, pixel by pixel," McCreary says.
As with any liquid-crystal display process, E Ink's flexible transistors and electronic ink displays required ultra-clean environments.
Site work on the E Ink facility began last February, was completed in mid-September, and was fully operational by the end of that same month, McCreary says. Although he declined to elaborate on how much the project cost, McCreary did say it came within the budget, but was about six weeks behind schedule because of long lead times on materials.
"The project cost was in the millions, and it was within the budget. We were almost on schedule," he says. "We were behind schedule because of delays on materials such as filters. The inspection and permit process took some time as well, and one inspector wanted roof access, so we had to go back and make those changes."
The cleanrooms were built by M-1 Systems (Ipswich, MA), which also designed and installed the HVAC and air handling systems that service both cleanrooms. Both cleanrooms use a reverse osmosis-deionized water system from Fluid Solutions (Lowell, MA). A gas handling system from AGA Process and piping by Amescor, both of Nashua, NH, funnels in needed saline, phosphine and ammonia, while BOC Edwards (Wilmington, MA) designed and installed effluent handling systems.
"It is an R&D cleanroom and a typical photolithography environment that has the unique ability to handle flexible substrates," McCreary says. "We can handle displays up to an 18-inch diagonal. Trying to handle something that floppy is a very different ball game."
Proprietary technology within the cleanrooms was designed to specifications based on two years of research, he says, adding that E Ink will work with traditional silicon-based, thin-film transistors as well as a variety of printed conductor and semiconductor materials, including organic and plastic transistors.
"We took standard semiconductor equipment and modified it to handle floppy materials," McCreary says. "This facility will allow us to turn new concepts around much quicker, we're hoping to learn as much in a month as we would in a year previous. It used to take us months, now it will take us a couple of weeks to turn new designs and processes."
E Ink employs about 90 people, 50 to 60 of whom work in research and development. "A handful" of researchers work in the cleanrooms. Personnel wear bunny suits, face covers and eye protection.
Positive air pressure within the cleanrooms is re-circulated at 60,000 cubic feet per minute (CFM), 8,000 CFM of which is made up of air from the outside. Temperatures are maintained at 68 degrees Fahrenheit with an RH of 45.
"It is a very quiet cleanroom," McCreary adds.
E Ink is searching for partners to adopt its electronic ink technology, but McCreary is most fascinated with how electronic ink could potentially change the way the world receives information.
"Instead of a displays found in a Palm Pilot or laptop, it will look and feel very much like paper," McCreary says. "It could mean flashing signs in supermarkets and electronic books. Imagine a newspaper being delivered once."
KEY FACTS
Size of facility: 9,500 square feet, 2000 of which is ISO Class 4 and Class 6 cleanroom space.
Purpose of facility: A research and development facility to devise flexible substrates for electronic ink displays.
Contractors: M-1 Systems (Ipswich, MA) designed and installed the cleanrooms, HVAC and air handling systems; Fluid Solutions installed a reverse osmosis-deionized water system. A gas handling system from AGA Process and piping by Amescor, both of Nashua, NH, funnels in needed siline phosphine and ammonia, while BOC Edwards (Wilmington, MA) designed and installed effluent handling systems.